The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1887-04-09
Correspondence Baltimore County Union.
SCIENTIFIC MISCELLANY.
Mystery. OF MAGIC M1ssoRs.


SCIENTIFIC MISCELLANY.
f.rs-s /. MYSTERY OF MAGIC MIssoRs. ssfl
The famous magic mirrors of japan and China
are circular. in form and from three to twelve
inches in diameter, with thick rim round the
edge. They are made from composition of copper
and tin, the rejecting surface being more or less
convex and polished with mercury analgam. On
: the back are raised designs-brds, flowers, drag
ons, geometrical patterns, or Japanese scenes and
myths--and the magical property lies in the fact
that when the rays of the sun are reflected from
the polished face on wall or screen the figures
are plainly visible in bright lines on darker
ground, though the back of the mirror is entirely
hidden from the light. For many centuries at
tempts at explanation have been made, but it has
remained for Messrs. Ayrton and Perry, the we'll
known English electricians, to practically demon
strate the real cause of the curious phenomenon
Their tests have shown that in the convexing pro-
cess the thinner parts of the mirror become slight
ly more rounded than the thicker tendency
which is increased by an expansive action of the
polishing mixture-and this gives an impercepti-
BILE irregularity to the surface which becomes APP
parent in the reflection. g.5l-
HH PROGRESS IN OYSTER FARMING.
In the extensive oyster culture experiments OF
the United States Government particular attention
is being given to methods representing the young
Wire baskets three feet square and six inches
deep are used for collecting the spat, which adj
here closely to the sides and bottom, this device
enabling the operators to prevent the accumula-
ton of mud, the great fee of the oyster industry,
by FREQUENT shakings of the baskets. An average
oyster is expected to yield 100000 young
POWER OF EXPLOSIVES.
Frightful as its possible effects over limited
space may be, the force lying dormant in ton OF
dynamite is by no means so formidable as many
are inclined to believe. Accurate measurements
nv italian engineers have shown that the explo-
sion of a ton dynmite exerts apower OF 1870
foot-tons that of a ton of nitrogycerine, 64,452
foot-tons and of ton of blasting gelatine, TO-
O50 foot-tons. A cube of II 900 tons Of ordinary
building stone would measure only 80 feet on the
side, and if it were possible to concentrate the
force of a ton of blasting gelatne at the moment
ofexplosion on such mass, the only effect would
be the lifting of the block to the height of foot
AN OLD OPERATION.
The surgical operation of trepanning or ire
phining the skull, few years ago discovered 10
have been common with prehistoric man, has since
been found to have continued in quite extensive
practice from the most remote period to our own
times A French anthropologist, M. Vedrenes,
mentions that native families of Montenegro and
of Algiers have made profession of. trepanning
for ages, and he notes, as curious circumstance
that the miners of Cornwall retain to the present
day the same implicit faith in the efficacy OF the
operation for the removal of blood-clots, ETC., in
head injuries that is held by these distant semi
barbarous tribes.
HEATING BY ELECTRICITY.
Among late French novelties is an electrical
heating stove In it the conducting wires are led
through apertures in plates ofrefractory clay and
plumbago, in which wire bebbins are placed as
part of the electric circuit. The bobbins are heat
ed by the passage of the current and in turn heat
the air which is allowed to pass freely through the
apparatus.
METEoRITE COLLECTIONS.
Itiscaimed that the largest collection of meteor
ties in the United States if not in the world is at
Amherst College. 1t embraces more than 5Oo
specimens, weighing about 1900 pounds. The
largest meteoric iron, procured from Colorado,
weighs 436 pounds, and the smallest, from New
York, half an ounce; the largest entire meteoric
stone, one from Ohio, weighs Sc pounds, and the
smallest, from Sweden, less than 50 grains. The
first specimen on the list fell in Alsace Nov 18th,
1892. The Yale College collection of meteorites
numbers 147, of weight of about 1856 pounds
The largest single mass known weighs 70 tons,
and is now in Stockholm; the next in size, weigh
ing 10 tons, is in Copenhagen; one of tons is at
the British Museum St. Petersburg has one of
1850 pounds Yale College, one of 1885 pounds;
and the Smithsonian Institution, one of 1,40O
pounds. ...sa.t
MISCELLANEOUS. ...f- ..-
An Italian, Signor GARRETT, claims to have dis
covered that fishes are attracted by music, and
has made successful demonstration Of the fact
on Lake Geneva by calling great numbers of fishes
about his boat. u
Probably the only medical Journal published
daily is Ell Diario Medtco, Pharmaceutical, of
Madrid.
In Persia and India efforts are being made to
stop the Importation of aniline dyes for use in
textile manufactures such as those of carpets and
brocades They are declared to be not only less
stable and artistic than the native dyes, but posi-
lively injurious to health. 2 E#.HEt
Though the celebrated experiment of squeezing
through the sides of gold vessel has been sup
posed to demonstrate the porosity of all matter,
while gases pass through metals much more read
ily the recent experiments of an Italian physicist
have shown that gases cannot be forced through
glass by any available mechanical, chemical or
electrical means. Even pressure of 1890 pounds
on the square inch had no effect.
At late meeting of the London Linnean So
ciety was exhibited volume of "Honzo Zufu
('Illustrations and Brief Descriptions of the
Plants of Japan'), by Imasatti Tsanemasa, which
consists of 90 volumes, containing, 600 colored
figures. The task of reproduction by native hand
labor isso great that only two or copies are
known to have been completed.
French surgeons disagree concerning the nature
of lockjaw. Some report having successfully
treated It as purely nervous affection, while
others insist that it is contagious disease, one
eminent observer contending that it is often con-
tracted by man through germs from horses.
Up to the present time 81 species of lilies have
become known, according to an English botanist,
Mr.. H. Elves
Older Sense, Horse Sense.
It is peasant to note the fact that Young Amer